1. Field of the Invention
The present invention is concerned with gas-operated motors and gas-supply apparatus therefor. In particular the invention relates to motors for which the working fluid is a non-burning gas which is condensible at familiar climatic temperatures under the action of pressure alone, for example carbon dioxide, water vapour, halocarbons such as the FREONS (Registered Trade Mark) and the like. An aim of the present invention is to provide means to use such gas-operated motors at much higher power levels than was practicable heretofore and, in particular to provide means to achieve a substantially improved economy of gas and energy usage.
2. Description of the Prior Art
Motors adapted to run on a supply of carbon dioxide are already well known. Usual versions of such motors employ a simple tank as a reservoir to contain a mixture of gaseous and liquid carbon dioxide under pressure from which the gas boils off to supply the motor during operation. This process causes the tank and the gas-liquid mixture within it to become rapidly colder, with a consequent and undesirable rapid fall in pressure of the gas in the tank causing falling motor power.
Methods and apparatus which overcome this problem are described in U.S. Pat. No. 4,092,830 which proposes the provision of one or more container(s) holding or capable of being charged with buffer substance(s) in heat-conductive relationship with the reservoir or with a passage through which, in operation, the gas is supplied from the reservoir to the motor. By the term `buffer substance` is meant a substance which undergoes a clange in its physical, chemical, crystallographic or other state at a temperature above the final operating temperature of the gas, the said change of state causing a release of heat to the gas or liquified gas. The choice and effects of suitable buffer substances are discussed in U.S. Pat. No. 4,092,830, the disclosure of which is incorporated herein by reference.